package com.dmall.list;

/**
 * 链表
 *
 * @author xiao1.wang@dmall.com
 * @date 2019-03-19 21:36:30
 */
public class LinkedList<E> {

    private class Node {

        public E e;
        public Node next;

        public Node(E e, Node next) {
            this.e = e;
            this.next = next;
        }

        public Node(E e) {
            this(e, null);
        }

        public Node() {
            this(null, null);
        }

        @Override
        public String toString() {
            return e.toString();
        }
    }

    private Node dummyHead;
    private int size;

    public LinkedList() {
        this.dummyHead = new Node(null, null);
        this.size = 0;
    }

    public int getSize() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    /*public void add(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Index is illegal.");
        }

        if (index == 0) {
            addFirst(e);
        } else {
            // 需要先找到插入索引的前一个节点位置
            Node prev = head;
            for (int i = 0; i < index - 1; i++) {
                prev = prev.next;
            }
            // Node node = new Node(e);
            // node.next = prev.next;
            // prev.next = node;
            prev.next = new Node(e, prev.next);
            size ++;
        }
    }*/

    public void add(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Index is illegal.");
        }

        // 需要先找到插入索引的前一个节点位置
        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        prev.next = new Node(e, prev.next);
        size ++;
    }

    public void addFirst(E e) {
        add(0, e);
    }

    public void addLast(E e) {
        add(size, e);
    }

    public E get(int index) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Index is illegal.");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        return cur.e;
    }

    public E getFirst() {
        return get(0);
    }

    public E getLast() {
        return get(size - 1);
    }

    public E set(int index, E newData) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Index is illegal.");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        E result = cur.e;
        cur.e = newData;
        return result;
    }

    public boolean contains(E e) {
        Node cur = dummyHead.next;
        while (cur != null) {
            if (cur.e.equals(e)) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    public E remove(int index) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Index is illegal.");
        }

        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        Node delNode = prev.next;
        prev.next = delNode.next;
        E result = delNode.e;
        delNode.e = null;
        delNode.next = null;
        size --;
        return result;
    }

    public E removeFirst() {
        return remove(0);
    }

    public E removeLast() {
        return remove(size - 1);
    }

    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        Node cur = dummyHead.next;
        while (cur != null) {
            res.append(cur.e).append("->");
            cur = cur.next;
        }
        /*for (Node cur = dummyHead.next; cur != null; cur = cur.next) {
            res.append(cur.e).append("->");
        }*/
        res.append("NULL");
        return res.toString();
    }
}
